Pair showed that adult cells can be reprogrammed to an embryonic state.

Two sets of experiments, performed 40 years apart, have been recognized with today's Nobel Prize in Physiology or Medicine. Cambridge University's John Gurdon won for showing that adult cells contain all the genetic information necessary to create every tissue in the body. That work set the stage for Shinya Yamanaka, who demonstrated that a relatively simple process could convert adult cells into embryonic stem cells. That development is already opening new avenues of research, and it holds the promise of new ways to repair tissues damaged by injury or disease.

As an embryo develops from a single fertilized egg, its cells become increasingly specialized. Although the initial cells can form any tissue in the body, groups of them adopt specific fates. A cell might first commit to being a neuron, after which it may be further limited to the roles required in the spinal cord, before finally specializing in the activities needed to control muscles. What doesn't seem to happen, however, is for the cell to switch developmental tracks—developing as, for example, a liver cell.

The apparent permanence of these fate decisions left most researchers thinking that they were in fact permanent—that the genomes of the cells undergo irreversible changes. At least in the case of immune cells, that seemed to be true: as part of generating the ability to recognize a diverse array of threats, B and T cells delete large stretches of their DNA and irreversibly commit themselves to recognizing a single threat.

But it's not true of all cells. John Gurdon performed key experiments back in the 1960s that showed how most cells maintain their general capacity to develop in any direction, although it took decades for the significance of his work to be fully appreciated. Using the eggs of a frog, Gurdon carefully removed the nucleus, which contains its genome. He then transferred in the nucleus of a specialized cell from an adult frog. If the general perception turned out to be correct, the DNA from that cell should have been permanently committed to its fate (in this case, intestine). Instead, Gurdon was able to get the hybrid cell to develop into a tadpole and, eventually, a healthy adult.

These results clearly demonstrated that adult cells contain all the genomic ingredients to make every cell in an organism. But it took time to develop the technology that took advantage of the fact. A key step in that development was honored by the Nobel Committee in 2007: the development of embryonic stem cells derived from mice. These cells, derived from early embryos, could divide indefinitely in culture without adopting any particular fate, but given the right chemical nudges, could form any type of adult cell. If injected into an early embryo, they would go on to contribute to every tissue—including the germ cells, which allowed these cells to go from a culture dish to future generations of mice.

This work led to the controversial development of human embryonic stem cells. But it also allowed people to ask what makes an embryonic stem cell distinct. Over time, scientists created a list of a few dozen genes that were consistently active in stem cells of various types. Some of these would undoubtedly be a consequence of the cells' stem-cell-ness. But others would be responsible for putting the cells there in the first place.

Shinya Yamanaka, an MD who says he got into research because he wasn't any good at surgery, decided to find out which of this list of genes was likely to be in control. Starting with about 20 known regulatory genes on the list, he inserted groups of them into adult cells, seeing which sets could turn them into a stem cell. By process of elimination, he gradually whittled that list down to just four genes. Inserting them into an adult cell would force it to get rid of any specializations and go on to adopt a stem cell fate. Once that was done, the cells could then be induced to form any type of adult cell in culture, or be injected into an embryo and contribute to an adult.

Stem cell work in general has raised the prospect that we could repair injured or damaged tissue with newly generated cells that are just as specialized as the ones they are replacing. But Yamanaka's work has turned that prospect into a vision of on-demand tissues, generated with a simple lab procedure, and a perfect genetic match for their recipient. The cells produced with the procedure he pioneered don't seem to be an exact match for cells derived from embryos, but it appears that they may be close enough that the difference doesn't matter.

It might be hard to imagine that research could take 40 years to come to fruition. But it's widely accepted that Gurdon's work fostered a change in perspective that was necessary for people to even start thinking about the studies that eventually led to stem cell manipulations. A year ago, I spoke to Martin Evans, who was a co-winner of the 2007 prize for stem cells, and he was already describing a long line of developments that led from Gurton through his own work and that of others, and that eventually culminated in Yamanaka's experiments. Two years ago, Gurdon and Yamanaka were honored with a Lasker Prize, which often precedes Nobel status.

That picture is clear now, but it remains staggeringly difficult to predict what areas of basic research will eventually lead to major breakthroughs. Gurdon's work wasn't immediately accepted at the time, and its significance wasn't widely recognized outside a small handful of developmental biologists. Only in retrospect can we see it for the breakthrough that it was.

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The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Skipping over what constitutes human life in this context, we still need to verify whether the adult stem cells we make are equivalent to their embryonic counterparts. Only one way to do that at the moment, and that's to use ESCs.

It's hard to understate how non-trivial this is, we're talking about de-programming a cell then re-programming it; lots and lots of potential for mishap. Get it wrong and you'll generate perpetually dividing, de-differentiated cells, i.e. a kind of cancer, or pre-cancer.

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I think that all Nobel prize winners should sport badass hair like this Gurdon guy.

On a more serious note, this is an awesome discovery. Not only is it a huge and fascinating deal on the science front, but it could potentially be an end-run around the moral objections to stem cell research.

I remember that for years scientists and pundits made fun of and derided opponents of embryonic stem cell research as halting the progress of science and medicine. That adult cells would never be as adaptable as ESCs. I've always had issues with ESC research and it relieves me to realize those people were wrong. That it was reasonable to fight ESC research and insist that we should work on transforming adult cells instead. I applaud these two Nobel Laureates on the contributions they made towards that end.

I definitely take the point that *all* fundamental research is important, and mindlessly culling branches of research that don't appear to have short-term benefit (for political reasons or otherwise) is incredibly foolish.

But, regarding "Stem Cells without ethical concerns," I want to raise an important point here:

It is only among particular ancient superstitions that embryonic stemcells have any deeper ethical bearing than adult/induced pluripotent stem cells. The real-life ethical concerns that require concern and introspection are common to both, and the whole point is that biologically, they are nearly interchangeable. As we learn more about controlling epigenetics, certainly this will only become more true.

There are countless concerns with scientific conduct, including ethical testing and treatment of disease, and we need to have adult conversations about the future of medicine and reproduction (and without getting distracted by certain non-specialists pre-emptively declaring that some blastocysts have a "soul").

Jumping the gun a little. Re-programming adult stem cells is by no means solved, and we still have to use ESCs as a yardstick. There is no dichotomy here, one technology benefits from the other.

Returning to the article, it's worth noting that eliminating genomic DNA is by no means far fetched. T and B cells are small beer compared to the parasite Ascaris suum, which does lose quite a bit of its genomic DNA in somatic cell lines.

I think that all Nobel prize winners should sport badass hair like this Gurdon guy.

On a more serious note, this is an awesome discovery. Not only is it a huge and fascinating deal on the science front, but it could potentially be an end-run around the moral objections to stem cell research.

"My hair is a bird. Your argument is invalid."

As to your point about avoiding moral objections, yes. The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Does (will) this render cord blood banks useless? Always seemed like they were a stop gap anyway.

No, blood banks will always exist. Their purpose is to aid in saving the life of a person suffering from a traumatic physical injury. Hospitals don't have time to pull out some cells and mass produce blood for the patient, they need blood and plasma immediately. Blood banks fulfill that need.

The same is even more true of battlefield trauma situations. Medics gotta have it RTFN, and blood banks provide it.

I remember that for years scientists and pundits made fun of and derided opponents of embryonic stem cell research as halting the progress of science and medicine. That adult cells would never be as adaptable as ESCs. I've always had issues with ESC research and it relieves me to realize those people were wrong. That it was reasonable to fight ESC research and insist that we should work on transforming adult cells instead. I applaud these two Nobel Laureates on the contributions they made towards that end.

Now we have Stem Cells without ethical concerns.

The image below pretty sums up my opinion on the matter of the debate between embryonic and adult stem cells. Use both and use them well, in my opinion.

The other way to look at it - if political and religious ideologies had not intervened, we would 10-20 years ahead in research for stem cell treatments by now, potentially saving hundreds of thousands of lives.

One more example of how religion and politics are limiting America's technical edge.

Tegid wrote:

I remember that for years scientists and pundits made fun of and derided opponents of embryonic stem cell research as halting the progress of science and medicine. That adult cells would never be as adaptable as ESCs. I've always had issues with ESC research and it relieves me to realize those people were wrong. That it was reasonable to fight ESC research and insist that we should work on transforming adult cells instead. I applaud these two Nobel Laureates on the contributions they made towards that end.

I remember that for years scientists and pundits made fun of and derided opponents of embryonic stem cell research as halting the progress of science and medicine. That adult cells would never be as adaptable as ESCs. I've always had issues with ESC research and it relieves me to realize those people were wrong. That it was reasonable to fight ESC research and insist that we should work on transforming adult cells instead. I applaud these two Nobel Laureates on the contributions they made towards that end.

Now we have Stem Cells without ethical concerns.

No. You were wrong then, and you're still wrong to oppose research using embryonic stem cells.

The advances that got us to the point where we can consider using adult cells for stem cell research (and eventually therapy) came through the use of embryonic stem cells. Patting yourself on the back for opposing this is truly deluded.

The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Skipping over what constitutes human life in this context, we still need to verify whether the adult stem cells we make are equivalent to their embryonic counterparts. Only one way to do that at the moment, and that's to use ESCs.

It's hard to understate how non-trivial this is, we're talking about de-programming a cell then re-programming it; lots and lots of potential for mishap. Get it wrong and you'll generate perpetually dividing, de-differentiated cells, i.e. a kind of cancer, or pre-cancer.

@Ads Without getting into an argument--because that's not my intention: A soul is an intangible; and our inability to quantify exactly what (or if) it exists is not something we should be 'guessing' at. I gathered from your comment an assumption that a soul is not possessed by a blastocyst; and that may be true. Yet since we cannot identify what a soul is, how are we to assess when a soul comes into being? To use an over-simplified example: when we started burning fossil fuels, did anyone give a second thought to whether or not there would be an environmental impact? No. It was only after significant breakthroughs in research and study that we reached a point where we were able to register and quantify the effects of greenhouse gasses on the environment, and even that has been debated heavily. Ethical concerns of this magnitude, when raised, should be respected until or unless they can *conclusively* be proven frivolous. By working around the objection, these scientists have achieved a giant leap towards serving the needs of humanity while avoiding the issue entirely. Brilliant.

As to your point about avoiding moral objections, yes. The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Research using human embryonic stem cells does not in any way destroy human life. The only way that could happen is if embryos were being created and then aborted specifically for the purpose of harvesting their stem cells. This does not and will never happen. Embryonic stem cells used for research are taken from aborted fetuses. Using them or not using them has no bearing on the likelihood of that fetus becoming a living, breathing baby since by definition an aborted fetus is not alive.

Does (will) this render cord blood banks useless? Always seemed like they were a stop gap anyway.

No, blood banks will always exist. Their purpose is to aid in saving the life of a person suffering from a traumatic physical injury. Hospitals don't have time to pull out some cells and mass produce blood for the patient, they need blood and plasma immediately. Blood banks fulfill that need.

He's not talking about those kinds of blood banks. He's talking about cord blood banks.

The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Skipping over what constitutes human life in this context, we still need to verify whether the adult stem cells we make are equivalent to their embryonic counterparts. Only one way to do that at the moment, and that's to use ESCs.

It's hard to understate how non-trivial this is, we're talking about de-programming a cell then re-programming it; lots and lots of potential for mishap. Get it wrong and you'll generate perpetually dividing, de-differentiated cells, i.e. a kind of cancer, or pre-cancer.

Yeah. So now we do not need for steam cells to solve particular problems, but for them to be identical with embryonic steam cells.

Use your gray cells more

We want steam cells to solve problems. Regardless if they are embryonic or not. If they do not solve those problems they are useless.

Also your statement is based on assumption that embryonic steam cell can be useful on large scale without any modifications. Thing that need proving.

The adult induced pluripontent stem cell work does not work around the soul issue or any other ethical issue. If anything, it makes it more complicated. If any adult somatic cell can be reverted to a pre-embryotic state, then every adult cell (so induced) has nearly the same potential for independent sentient life as a fertilized egg. Moreover, until we completely understand epigenetic changes in adult cells, that method is far more likely to lead to aberrations.

But, that's only one problem, and one of the least likely to come up, since no one actually wants to grow adult clones like in crappy SciFi movies.

When it comes to stem cell therapies, regardless of the cell source, how do you adequately test therapies for human use? When it comes to these very deep genetic and epigenetic manipulations, success in animal models will not be enough to assure even basic safety for human therapy, since subtle differences in genetic and epigenetic data are precisely the difference between, say, mice and chimps and humans.

Edit: to clarify more --- there is nothing essentially magical about pluripotent cells derived from sexual intercourse versus those derived by modern biochemistry. That's why the research is so amazing, but people hung up on the sequence of inferences "sex ==> embryo ==> person ==> soul" and its false converse are missing both the amazing discoveries in biology and the subtleties of morality.

There are countless concerns with scientific conduct, including ethical testing and treatment of disease, and we need to have adult conversations about the future of medicine and reproduction (and without getting distracted by certain non-specialists pre-emptively declaring that some blastocysts have a "soul").

Sorry, but I just can't hear it any longer. There is simply no ethics to cell research.

Cells are cells. Not more.

They are lacking the key ingredient of an impact on humans to become ethical.

No doubt the prize winning work is worthy of being honored. But prizes have more to do with the needs of the prize givers than with the uniqueness of the work that is honored. Automation is the factor that has made the qualitative difference in the recent progress in biological science. It is already more accurate to think of biological science as a Moore's law style industrialized process that is systematically scaling up our understanding of life's central mechanisms and our ability to control them than it is to think of science as the work of a few unique high priests who erratically bless us by revealing some exceptional truth..The recent set of papers from the ENCODE consortium ( http://dx.doi.org/10.1038/nature11247 )provides an example that relates to the prize winning work. One of the major objectives of that work is achieving an encyclopedic understanding of the histone marks and associated DNA sequences that are the central epigenetic factors controlling cell types and developmental programs. That work seems well on its way towards achieving the kind of engineering understanding of cellular processes that is needed to really make stem cells do what someone wants them to do.It may turn out that people manage to find uses for stem cells that don't depend on much of an understanding about how the cell really works. But, a thorough understanding of stem cells is likely to come as part of a process that achieves enough understanding and control over biochemical processes to make it possible to create cells from chemical parts. That kind of process has already been possible for viruses for something like a decade. It is hard to believe that anything more than a few more turns of the crank is required to scale that kind of process up to a complete cell. The work of a large number of relatively talented scientists and engineers will be required for the process. But the kinds that our research institutes and tech companies are able to find regularly in relatively large numbers should be more than adequate for the task.

I'm not going to get into the ethics argument about this, b/c it's subjective and everyone's passionate about their stance on it.

But, from a technical aspect, a lot of the human body is still a big mystery. Every day folks feel held hostage to their biology due to genetic-based diseases or cause-effect situations they can't even determine.

"Did I get cancer, b/c I'm genetically pre-disposed, or was it something I ate, or did I sit in the sun too long? Why me?"

If we can do research like this to master our biology, then more power to us. I'm wondering if this is one step closer to immortality. If we revert a cell back to stem cell state, does it reset its duplication ability? Or, are we just stripping out its specialization, but if it's already lived a long life then the cell still won't live for much longer?

There are countless concerns with scientific conduct, including ethical testing and treatment of disease, and we need to have adult conversations about the future of medicine and reproduction (and without getting distracted by certain non-specialists pre-emptively declaring that some blastocysts have a "soul").

Sorry, but I just can't hear it any longer. There is simply no ethics to cell research.

Cells are cells. Not more.

They are lacking the key igredient of an impact on humans to become ethical.

Dio82,

What you've just expressed is a literal example of reductio ad absurdum. It's just as wrong as saying:"There is simply no ethics to journalism. Ink and paper is ink and paper. Not more." or"There is simply no ethics to ethics to missle research. Fluid mechanics is fluid mechanics. Not more."

Every human activity has ethical consequences.

The view I am expressing above is that there are important ethical concerns, and that the publicly popular discussions about souls and religious complaints are a pointless, intellectually vacuous distraction from the real, more important, and more mundane issues that surround all research that will ultimately be used in medicine.

Edit: with that, I'll stop being distracted by it and get back to work... with science!

If we can do research like this to master our biology, then more power to us. I'm wondering if this is one step closer to immortality. If we revert a cell back to stem cell state, does it reset its duplication ability? Or, are we just stripping out its specialization, but if it's already lived a long life then the cell still won't live for much longer?

Last I checked, the latter is the case, if memory serves the limit on the number of times a given cell can replicate has to do with the length of the telomere caps on the end of the DNA molecule, which shorten with each replication cycle. Inducing an adult cell into a pluripotent state doesn't alter that aspect. Someone more knowledgeable can correct me if I'm wrong, it's been a while.

The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Skipping over what constitutes human life in this context, we still need to verify whether the adult stem cells we make are equivalent to their embryonic counterparts. Only one way to do that at the moment, and that's to use ESCs.

It's hard to understate how non-trivial this is, we're talking about de-programming a cell then re-programming it; lots and lots of potential for mishap. Get it wrong and you'll generate perpetually dividing, de-differentiated cells, i.e. a kind of cancer, or pre-cancer.

Yeah. So now we do not need for steam cells to solve particular problems, but for them to be identical with embryonic steam cells.

Use your gray cells more

We want steam cells to solve problems. Regardless if they are embryonic or not. If they do not solve those problems they are useless.

Also your statement is based on assumption that embryonic steam cell can be useful on large scale without any modifications. Thing that need proving.

I really haven't the faintest idea what you are on about.

That said I feel something ought to be explained here: Stem cells, whatever their origin, give rise to differentiated cells (e.g. muscle cells). Their utility is derived from this ability to make more of something else. If I have damaged a tissue/cell my body cannot normally replace then manufacturing an appropriate stem cell to make repairs would be a great fix.

Making repairs with a reprogrammed adult stem cell would be even better as they could use my own genetic material and therefore stand a very low chance of immunological rejection.

The trouble arises when trying to determine how my adult stem cells should behave, especially if naturally occurring stem cells aren't present (or are difficult to coax into action, e.g. nerve cell progenitors). How to proceed then? One answer is to got back to source and look at the only stem cells that normally can give rise to any tissue (known as totipotent in the scientific jargon). Those cells are, of course, embryonic in origin.

You may not like it, and I support your right to object, nevertheless there's good rational behind ESC research and ultimately it will support adult stem cell research,

what is the difference between adult and embryonic stem cells? how are they taken out of adults?

during the birth of my children we were asked if we wanted to store or donate stem cells from the blood in the umbilical cord. we said sure to donating them, would the cells from the cord blood be considered embryonic? and if so doesn't that defeat the argument that the child has to die to obtain them?

I only wanted to comment this issue, but it got me thinking.Obtaining absolute knowledge of this universe, populating and researching it, if the universe will continue expanding forever, is probably what will continue driving humans forever. Growth and expansion are what is necessary for this. There's more than enough resources and manpower on this world to continue at this rate for a bit, which is somehow overcrowded by people owing other people money. That just seems to be how the economic system works. It doesn't make any sense (concept), but it would take quite a lot of effort to change it, so why not let it be? It isn't really necessary for anybody to starve, you just have to divide it equally. Taking that into account we continue, and start improving investments into research.To those opposed to this: If a mother and father (excepting accounts of rape etc., his opinion should be heard out too) agree that they can't raise a child, why not let it be aborted, and be used to help other, living humans? If people offer their body to research after they die, why not let them help other people? Isn't that something good? Cloning is a special case. Humans are built upon experiences. Even if you would for example put clones into special facilities or try to give them similar surroundings, they would never be the same. Similar, probably, but not the same. I think it's unnecessary, because it would lead to overpopulation quickly. Widows cloning husbands, parents cloning dead children, armies being raised, research facilities etc. So it should probably be made illegal, even if scientific break through were possible because of it.I'll stop now, and I've missed a few jumps in logic to write this down, so you may find mistakes.

EDIT: I missed out quite an important thing I wanted to say: Why not use what people who willingly offer themselves science? Don't force your belief on others when they aren't hurting anyone.

On a slightly separate, but relevant note, it remains to be seen how successful it is to really de-differentiate a cell to become an IPSC then turn it into another cell. There is evidence from George Daley and colleagues that cells retain epigenetic "memory" (http://www.ncbi.nlm.nih.gov/pubmed/20644535). Also, cells are likely to gather more mutations in genes irrelevant to their lineage. E.g. a cell going down a muscle lineage will undergo silencing of genes which would be active in liver such as albumin. If that copy of the albumin gene is mutated, it means little for the cell living on muscle beach. However when the poor thing gets sox'ed, klf-ed, myc-ed and oct-ed, and sent careering towards a liver cell lineage, it won't fare so well because that albumin gene is borked.

during the birth of my children we were asked if we wanted to store or donate stem cells from the blood in the umbilical cord. we said sure to donating them, would the cells from the cord blood be considered embryonic? and if so doesn't that defeat the argument that the child has to die to obtain them?

Hmm all kinds of complicated and I'm just off to bed... I'll leave the first part to other posters. As for the rest, to cut a long story short, there are stem cells and there are stem cells (rough guide here).

Some stem cells can be anything they're programmed to be, these are known as totipotent stem cells, embryonic stem cells fit this description.

Some stem cells can give rise to a number of cell types but not everything, these are known as pluripotent. Early(ish) embryo cells fall into this category, as the embryo differentiates into germ layers, daughter cells become restricted to particular fates:

ectoderm gives rise to cells forming the nervous system and other tissues I can't recall off the top of my head,

mesoderm give rise to blood muscle etc.

endoderm becomes epithelial cells.

Further down the line, cell fate is typically restricted further, and cells become "merely" multipotent. Stem cells derived from the umbilical cord fit in here. They can give rise to bone marrow tissue, which is itself a kind of stem cell supply for your red and white blood cells. They won't differentiate into anything else (e.g. a neuron) but they are still stem cells.

On a slightly separate, but relevant note, it remains to be seen how successful it is to really de-differentiate a cell to become an IPSC then turn it into another cell. There is evidence from George Daley and colleagues that cells retain epigenetic "memory" (http://www.ncbi.nlm.nih.gov/pubmed/20644535). Also, cells are likely to gather more mutations in genes irrelevant to their lineage. E.g. a cell going down a muscle lineage will undergo silencing of genes which would be active in liver such as albumin. If that copy of the albumin gene is mutated, it means little for the cell living on muscle beach. However when the poor thing gets sox'ed, klf-ed, myc-ed and oct-ed, and sent careering towards a liver cell lineage, it won't fare so well because that albumin gene is borked.

Excellent points. And the epigenetic part is what I alluded to in one of my earlier posts. Very difficult to "format" cells. (Not that a full format would be desirable either!)

I guess we'll be able to regrow parts of our own body from our own stem cells one day soon in the future! That'll make it somewhat easier for things such as heart or lung transplants, maybe even bone marrow?

Science seems to be advancing at an astonishing rate! I guess one day we might even be able to replace our body parts with mechanical replacements or organic ones that are superior to what we were born with. The future seems rather scary.... and exciting.

I guess we'll be able to regrow parts of our own body from our own stem cells one day soon in the future! That'll make it somewhat easier for things such as heart or lung transplants, maybe even bone marrow?

Science seems to be advancing at an astonishing rate! I guess one day we might even be able to replace our body parts with mechanical replacements or organic ones that are superior to what we were born with. The future seems rather scary.... and exciting.

A good first step is doing things like growing replacements of relatively simple, but not self-repairing tissues. For example, nerve tissue, especially spinal cord tissue. We could literally heal the lame, after months of agonising physiotherapy of course. It could also be use to treat conditions like diabetes (type 1) where the pancreas is non-functional, grow a new one.

The problem with limbs is that they are very complicated and made of lots of different tissues. I'm sure one day we'll be able to do it, but there are far more likely possibilities much sooner!

The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Skipping over what constitutes human life in this context, we still need to verify whether the adult stem cells we make are equivalent to their embryonic counterparts. Only one way to do that at the moment, and that's to use ESCs.

It's hard to understate how non-trivial this is, we're talking about de-programming a cell then re-programming it; lots and lots of potential for mishap. Get it wrong and you'll generate perpetually dividing, de-differentiated cells, i.e. a kind of cancer, or pre-cancer.

Tyrell: The facts of life... to make an alteration in the evolvement of an organic life system is fatal. A coding sequence cannot be revised once it's been established.Roy: Why not?Tyrell: Because by the second day of incubation, any cells that have undergone reversion mutation give rise to revertant colonies, like rats leaving a sinking ship; then the ship... sinks.Roy: What about EMS-3 recombination?Roy: We've already tried it - ethyl, methane, sulfinate as an alkylating agent and potent mutagen; it created a virus so lethal the subject was dead before it even left the table.Roy: Then a repressor protein, that would block the operating cells.Tyrell: Wouldn't obstruct replication; but it does give rise to an error in replication, so that the newly formed DNA strand carries with it a mutation - and you've got a virus again... but this, all of this is academic. You were made as well as we could make you.

The flip side of that is that embryonic stem cell research might lose funding; there doesn't seem to be a good reason to use embryonic stem cells at this point if they are potentially destroying human life...

Skipping over what constitutes human life in this context, we still need to verify whether the adult stem cells we make are equivalent to their embryonic counterparts. Only one way to do that at the moment, and that's to use ESCs.

It's hard to understate how non-trivial this is, we're talking about de-programming a cell then re-programming it; lots and lots of potential for mishap. Get it wrong and you'll generate perpetually dividing, de-differentiated cells, i.e. a kind of cancer, or pre-cancer.

Tyrell: The facts of life... to make an alteration in the evolvement of an organic life system is fatal. A coding sequence cannot be revised once it's been established.Roy: Why not?Tyrell: Because by the second day of incubation, any cells that have undergone reversion mutation give rise to revertant colonies, like rats leaving a sinking ship; then the ship... sinks.Roy: What about EMS-3 recombination?Roy: We've already tried it - ethyl, methane, sulfinate as an alkylating agent and potent mutagen; it created a virus so lethal the subject was dead before it even left the table.Roy: Then a repressor protein, that would block the operating cells.Tyrell: Wouldn't obstruct replication; but it does give rise to an error in replication, so that the newly formed DNA strand carries with it a mutation - and you've got a virus again... but this, all of this is academic. You were made as well as we could make you.